Update actions/upload-artifact to v4

Author: BadMagic100

.github/workflows/dotnet.yml

@@ -43,7 +43,7 @@ jobs:
       run: dotnet test Archipelago.MultiClient.Net.Tests/bin/Release/net48/Archipelago.MultiClient.Net.Tests.dll -l "trx;LogFileName=TestResults_standard20.trx"
 
     - name: Upload Test Results
-      uses: actions/upload-artifact@v2.3.1
+      uses: actions/upload-artifact@v4
       with:
         name: TestResults
         path: TestResults/*.trx